In micro-processing for manufacturing a semiconductor device or a FPD (Flat Panel Display) using plasma, it is very important to control a temperature or a temperature distribution of a processing target substrate (a semiconductor wafer, a glass substrate, etc.) as well as to control a plasma density distribution on the processing target substrate. If the temperature control of the substrate is not properly performed, not only the uniformity of a surface reaction of the substrate but also the uniformity of process characteristics may not be achieved, so that a production yield of semiconductor devices or display devices is decreased.
In general, a mounting table or susceptor, which mounts thereon a processing target substrate within a chamber of a plasma processing apparatus (particularly, a capacitively coupled plasma processing apparatus), has a function as a high frequency electrode that applies a high frequency power into a plasma space, a function as a holder that holds thereon the substrate by electrostatic attraction or the like, and a function as a temperature controller that controls the temperature of the substrate to a preset temperature through heat transfer. As for the temperature control function, it is required to appropriately correct a heat input characteristic distribution of the substrate affected by non-uniform radiant heat from plasma or a wall of the chamber, or a heat distribution affected by a substrate supporting structure.
Conventionally, in order to control the temperature of the susceptor and, further, the temperature of the substrate, a heater structure is widely employed. In this heater structure, a heating element that generates heat by an electric current applied thereto is provided in the susceptor, and Joule heat generated by the heating element is controlled. When using this heater structure, however, a part of a high frequency power applied to the susceptor from a high frequency power supply may be easily introduced into a heater power feed line through the heating element as a noise. If this high frequency noise reaches a heater power supply through the heater power feed line, operation and performance of the heater power supply is degraded. Furthermore, if a high frequency current flows in the heater power feed line, the high frequency power may be wasted. Typically, to solve these problems, a filter that reduces or blocks the high frequency noise flowing from the heating element embedded in the susceptor is provided on the heater power feed line. Typically, this kind of filter is provided outside the chamber (processing vessel) to be located directly under the susceptor.
The present applicant describes, in Patent Document 1, a filter technique that provides improved filter performance for blocking a high frequency noise introduced to a line such as a power feed line or a signal line from an electrical member other than a high frequency electrode within a processing vessel of a plasma processing apparatus. This filter technique employs a regular multiple parallel resonance characteristic of a distributed constant line. Accordingly, only one air coil is provided within the filter.    Patent Document 1: Japanese Patent Laid-open Publication No. 2011-135052